Salva, I am having the exact same issue. WC API works fine for me, but using the endpoints provided in the documentation only returns a 404: "rest_no_route" response. I am using Postman to test a GET response using URL: https://[mywebsite]/wp-json/wc/v3/atum/inventories/?consumer_key=ck[mykey]&consumer_secret=cs[mysecret]
Again, if I change the endpoints to one listed in the WC API I have no problems, it is only throwing an error when trying to retrieve from the ATUM API. I have ensured the ATUM API is turned on in settings. Any help would be appreciated. Thanks!